how can I add auto layout constraints for a line programatically

Question

I drew a line programatically in y UI. How can I add constraints for this line.

let line = UIView(frame: CGRect(x: 10, y: 350, width: 350, height: 1))
line.backgroundColor = UIColor.white;self.view.addSubview(line)

Danh Huynh · Accepted Answer · 2017-03-28T06:55:34.063

2

I created a red line: height = 1, top = 50 and the width will be flexible You can modify the position as you want.

override func viewDidAppear(_ animated: Bool) {
    super.viewDidAppear(animated)

    let line = UIView()
    line.backgroundColor = UIColor.red
    view.addSubview(line)

    line.translatesAutoresizingMaskIntoConstraints = false

    let leadingConstraint = NSLayoutConstraint(item: line, attribute: .left, relatedBy: .equal, toItem: view, attribute: .left, multiplier: 1.0, constant: 20.0)
    let topConstraint = NSLayoutConstraint(item: line, attribute: .top, relatedBy: .equal, toItem: view, attribute: .top, multiplier: 1.0, constant: 50.0)
    let trailingConstraint = NSLayoutConstraint(item: view, attribute: .right, relatedBy: .equal, toItem: line, attribute: .right, multiplier: 1.0, constant: 20.0)
    let heightConstraint = NSLayoutConstraint(item: line, attribute: .height, relatedBy: .equal, toItem: nil, attribute: .notAnAttribute, multiplier: 1.0, constant: 1.0)

    view.addConstraints([topConstraint, leadingConstraint, trailingConstraint, heightConstraint])
}

The result!

edited Mar 28 '17 at 06:55

answered Mar 28 '17 at 06:30

Danh Huynh

2,337
1
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Sorry mate.I am just getting a white screen when i tried your code.Why is it not coming for me. – faheem Mar 28 '17 at 06:47
Let copy my code and paste in **viewDidAppear** method. Is it working? – Danh Huynh Mar 28 '17 at 06:52
Or you set the line's color to white? – Danh Huynh Mar 28 '17 at 07:17
no. i just copy paste your code exactly as it is.still i am not getting it – faheem Mar 28 '17 at 07:34
Let create a new project and try with my code. Will be it working? – Danh Huynh Mar 28 '17 at 07:37
@faheem Constraints are right and they are properly working. – dahiya_boy Mar 28 '17 at 10:28
thank you so much bro..thats working fine now. thanks for the help.@DanhHuynh – faheem Mar 28 '17 at 11:09

score 1 · Answer 2 · answered Mar 28 '17 at 06:13

1

NSLayoutConstraint Style

NSLayoutConstraint(item: line, attribute: NSLayoutAttribute.CenterX, relatedBy: NSLayoutRelation.Equal, toItem: view, attribute: NSLayoutAttribute.CenterX, multiplier: 1, constant: 0).active = true
NSLayoutConstraint(item: line, attribute: NSLayoutAttribute.CenterY, relatedBy: NSLayoutRelation.Equal, toItem: view, attribute: NSLayoutAttribute.CenterY, multiplier: 1, constant: 0).active = true`

answered Mar 28 '17 at 06:13

tabassum

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Thanks for a quick response. But this is not making any changes to the line. if i change the model in simulator, the line is not appearing in the same place.@tabassum – faheem Mar 28 '17 at 06:16

how can I add auto layout constraints for a line programatically

2 Answers2